Electric energy storage device, fault diagnosis method

Abstract

To improve the failure diagnosis accuracy of a relay.SOLUTION: A power storage device 50 includes: an external terminal 51; a power storage cell 60; a relay 53 having one end electrically connected to the external terminal 51 and the other end electrically connected to the power storage cell 60; and a failure diagnosis device 150. The relay 53 is a normally closed type latching relay including a contact 53a, a first coil 53b keeping the contact 53a closed, by the supply of excitation current Is from the power storage cell 60, and a second coil 53d keeping the contact 53a open, by the supply of excitation current Ir from the power storage cell 60. The failure diagnosis device 150 keeps the contact 53a closed by the supply of the excitation current Is to the first coil 53b from the power storage cell 60, in failure diagnosis processing of the relay, and diagnoses an open failure of the relay 53 based on a voltage change ΔV1 at the external terminal 51 before and after the supply of the excitation current.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a technique for diagnosing a failure of a relay.

Background Art

[0002] A battery mounted on a vehicle such as an automobile has a relay, and when detecting any abnormality, it protects the battery by cutting off the current (see Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When a relay for a vehicle fails and becomes stuck open, the power supply to the vehicle may be interrupted, and the vehicle may experience a power fail (loss of power). Therefore, it is required to diagnose an open failure of the relay. Also, in applications other than vehicles, when power fail is not allowed, it is required to diagnose an open failure of the relay. One aspect of the present invention discloses a technique for diagnosing an open failure of a relay.

Means for Solving the Problems

[0005] The power storage device includes an external terminal, a power storage cell, a relay having one end electrically connected to the external terminal and the other end electrically connected to the power storage cell, and a fault diagnosis device. The relay is a normally-closed type latching relay including a contact, a first coil that holds the contact in a closed state when an exciting current is supplied from the power storage cell, and a second coil that holds the contact in an open state when an exciting current is supplied from the power storage cell. The fault diagnosis device holds the contact in a closed state by supplying an exciting current from the power storage cell to the first coil in the fault diagnosis process of the relay, and diagnoses an open fault of the relay based on a voltage change of the external terminal before and after the supply of the exciting current.

[0006] This technology can also be applied to a relay fault diagnosis method and a fault diagnosis program.

Advantages of the Invention

[0007] This technology can diagnose an open fault of a relay.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

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Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Embodiment for Carrying Out the Invention

[0009] Describe the outline of the power storage device. The power storage device includes an external terminal, a power storage cell, a relay having one end electrically connected to the external terminal and the other end electrically connected to the power storage cell, and a fault diagnosis device. The relay is a normally closed type latching relay including a contact, a first coil that holds the contact in a closed state when an exciting current is supplied from the power storage cell, and a second coil that holds the contact in an open state when an exciting current is supplied from the power storage cell. In the fault diagnosis process of the relay, the fault diagnosis device supplies an exciting current from the power storage cell to the first coil to hold the contact in a closed state, and diagnoses an open fault of the relay based on the voltage change of the external terminal before and after the supply of the exciting current.

[0010] In this configuration, for example, when the power storage device is for a vehicle, regardless of the state of the vehicle system, it is possible to accurately determine whether the contact is "open" or "closed". Therefore, an open fault of the relay can be accurately diagnosed. By improving the fault diagnosis accuracy, an open fault of the relay can be detected early. When an open fault of the relay is detected, it is possible to reduce the risk of the vehicle suffering a power failure by taking necessary measures such as operating a redundant circuit.

[0011] In this configuration, when the contact is switched from "closed" to "open" due to a malfunction of the relay or the like, the contact can be returned to the "closed" state by executing a fault diagnosis. Therefore, the risk of the vehicle suffering a power failure can be reduced.

[0012] That is, with this configuration, since "early detection of open failures" and "closing return after malfunction" are possible, the risk of power failure can be reduced and the reliability of the power storage device can be improved. This effect is the same when using a power storage device in applications that do not allow power failure, not limited to vehicles.

[0013] The failure diagnosis device may diagnose an open failure of the relay based on a comparison result between a voltage change of the external terminal before and after the supply of the exciting current and a voltage change of the power storage cell.

[0014] When determining the "open" and "closed" states of the contact only based on the voltage change of the external terminal before and after the supply of the exciting current, if the voltage of the external terminal changes due to factors other than the supply of the exciting current, there is a possibility of misjudging the state of the contact. With this configuration, by comparing the voltage change of the external terminal with the voltage change of the power storage cell, even when the voltage of the external terminal changes due to factors other than the supply of the exciting current, it is possible to accurately determine whether the contact is "open" or "closed".

[0015] The failure diagnosis device may repeatedly execute the failure diagnosis process of the relay at a predetermined execution cycle. With this configuration, a contact that has been switched to "open" due to a malfunction of the relay can be returned to "closed" at a predetermined execution cycle. Therefore, it is possible to prevent the contact switched due to a malfunction from remaining in the open state for a long time.

[0016] <Embodiment 1> 1. Description of Battery 50 As shown in FIG. 1, the vehicle 10 is equipped with an engine 20 and a battery 50 used for starting the engine 20 and the like. The battery 50 is an example of a "power storage device". Instead of the engine 20 (internal combustion engine), a power storage device for vehicle driving or a fuel cell may be mounted on the vehicle 10.

[0017] As shown in FIG. 2, the battery 50 includes an assembled battery 60, a circuit board unit 65, and a container 71. The container 71 includes a main body 73 made of a synthetic resin material and a lid 74. The main body 73 has a bottomed cylindrical shape and includes a bottom surface portion 75 and four side surface portions 76. An opening 77 is formed at the upper end of the main body 73 by the four side surface portions 76.

[0018] The container 71 houses the assembled battery 60 and the circuit board unit 65. The circuit board unit 65 is a board unit on which various components (such as a relay 53, a current detection unit 54 shown in FIG. 5, and a management device 150, etc.) are mounted on a circuit board 100, and is arranged adjacent to, for example, above the assembled battery 60 as shown in FIG. 2. Alternatively, the circuit board unit 65 may be arranged adjacent to the side of the assembled battery 60.

[0019] The lid 74 closes the opening 77 of the main body 73. An outer peripheral wall 78 is provided around the lid 74. The lid 74 has a protruding portion 79 that is substantially T-shaped in plan view. Of the front portion of the lid 74, a positive external terminal 51 is fixed to one corner, and a negative external terminal 52 is fixed to the other corner. The circuit board unit 65 may be housed in the lid 74 (for example, inside the protruding portion 79) instead of the main body 73 of the container 71.

[0020] The assembled battery 60 is composed of a plurality of cells 62. As shown in FIG. 4, each cell 62 houses an electrode body 83 together with a non-aqueous electrolyte in a rectangular parallelepiped-shaped (prismatic) case 82. The cell 62 is, for example, a lithium-ion secondary battery cell. The case 82 has a case body 84 and a lid 85 that closes the opening above it.

[0021] Although not shown in detail, the electrode body 83 is formed by disposing a separator made of a porous resin film between a negative electrode plate obtained by applying an active material to a base material made of a copper foil and a positive electrode plate obtained by applying an active material to a base material made of an aluminum foil. All of these are in strip shape, and are wound flatly so as to be accommodated in the case body 84 with the negative electrode plate and the positive electrode plate being shifted in position to opposite sides in the width direction with respect to the separator. Instead of the wound type, the electrode body 83 may be of a stacked type.

[0022] A positive electrode terminal 87 is connected to the positive electrode plate via a positive electrode current collector 86, and a negative electrode terminal 89 is connected to the negative electrode plate via a negative electrode current collector 88. The positive electrode current collector 86 and the negative electrode current collector 88 each have a flat pedestal portion 90 and a leg portion 91 extending from the pedestal portion 90. A through hole is formed in the pedestal portion 90. The leg portion 91 is connected to the positive electrode plate or the negative electrode plate.

[0023] The positive electrode terminal 87 and the negative electrode terminal 89 each consist of a terminal main body portion 92 and a shaft portion 93 protruding downward from the center portion of the lower surface thereof. The terminal main body portion 92 and the shaft portion 93 of the positive electrode terminal 87 are integrally formed of aluminum (a single material). In the negative electrode terminal 89, the terminal main body portion 92 is made of aluminum and the shaft portion 93 is made of copper, and these are assembled. The terminal main body portions 92 of the positive electrode terminal 87 and the negative electrode terminal 89 are disposed at both ends of the lid 85 via gaskets 94 made of an insulating material, and as shown in FIG. 3, they are exposed outward from the gaskets 94.

[0024] The lid 85 has a pressure release valve 95. The pressure release valve 95 is located between the positive electrode terminal 87 and the negative electrode terminal 89. The pressure release valve 95 is a safety valve. The pressure release valve 95 opens when the internal pressure of the case 82 exceeds the limit, and reduces the internal pressure of the case 82.

[0025] FIG. 5 is a block diagram showing the electrical configuration of the battery 50. The battery 50 includes an assembled battery 60, a relay 53, a current detection unit 54, a measurement IC 110, a redundant circuit 120, a voltage drop circuit 130, and a management device 150.

[0026] The battery 50 is electrically connected to an alternator 160 that is a generator powered by the engine 20 and an in-vehicle electrical load 170.

[0027] When the amount of power generated by the alternator 160 is greater than the power consumption of the electrical load 170 during operation of the engine 20, the battery 50 is charged by the alternator 160. When the amount of power generated by the alternator 160 is less than the power consumption of the electrical load 170, the battery 50 discharges to make up for the shortfall.

[0028] When the engine 20 is stopped, the alternator 160 stops generating power. During power generation stop, the battery 50 is not charged and only discharges to the electrical load 170.

[0029] The cells 62 of the battery pack 60 are, for example, twelve (see FIG. 2) and are connected in 3 parallel and 4 series. FIG. 5 shows three cells 62 connected in parallel represented by one battery symbol. The cell 62 is an example of a "storage cell". The storage cell is not limited to a prismatic cell and may be a cylindrical cell or a pouch cell having a laminated film case.

[0030] The battery pack 60, the relay 53, and the current detection unit 54 are connected in series via a power line 55P and a power line 55N. The power lines 55P and 55N can use a bus bar BSB (see FIG. 2), which is a plate-shaped conductor made of a metal material such as copper.

[0031] As shown in FIG. 5, the power line 55P connects the positive external terminal 51 and the positive electrode of the battery pack 60. The power line 55N connects the negative external terminal 52 and the negative electrode of the battery pack 60. The external terminals 51 and 52 are terminals for connection to the vehicle 10, and the battery 50 can be electrically connected to the alternator 160 and the electrical load 170 via the external terminals 51 and 52.

[0032] Relay 53 is provided on the positive power line 55P, electrically connecting one end to the external terminal 51 of the positive electrode and the other end to the positive electrode of the assembled battery 60. In this specification, one end and the other end of relay 53 mean the electrical connection points of relay 53. One end may be the first terminal of the relay, and the other end may be the second terminal of the relay. The first terminal and the second terminal of the relay may be provided on different surfaces (or different sides in plan view) of the relay housing, or may be provided on the same surface (or the same side in plan view).

[0033] Relay 53 is a self - holding latching relay and includes, as shown in FIG. 6, a contact 53a, a set coil 53b, a switch 53c, a reset coil 53d, and a switch 53e. The set coil 53b and the reset coil 53d are connected to the positive electrode of the assembled battery 60, and the exciting currents Is and Ir are supplied using the assembled battery 60 as a power source. The set coil 53b is the "first coil", and the reset coil 53d is the "second coil".

[0034] By closing switch 53c and flowing the exciting current Is from the assembled battery 60 to the set coil 53b, the contact 53a can be held in the closed state. By closing switch 53e and flowing the exciting current Ir from the assembled battery 60 to the reset coil 53d, the contact 53a can be held in the open state.

[0035] As shown in FIG. 7, continuous energization of the exciting current Is is not required. If a pulsed exciting current Is is supplied to the set coil 53b, then even after interrupting the exciting current Is, the contact 53a can be maintained in the closed state. Similarly, if a pulsed exciting current Ir is supplied to the reset coil 53d, then even after interrupting the exciting current Ir, the contact 53a can be maintained in the open state.

[0036] Relay 53 is of the normally closed type. Normally, contact 53a is held in the "closed" state. When there is any abnormality in battery 50, switch 53e is turned on to supply exciting current Ir to reset coil 53d, and by switching contact 53a of relay 53 from "closed" to "open", the current I of battery pack 60 can be cut off.

[0037] As shown in FIG. 5, current detection unit 54 is provided on negative power line 55N. Current detection unit 54 may be a shunt resistor. The resistive current detection unit 54 can measure the current I of battery pack 60 based on the voltage Vr across both ends of current detection unit 54. The resistive current detection unit 54 can distinguish between discharge and charge from the polarity (positive or negative) of the voltage. Alternatively, current detection unit 54 may be a magnetic sensor.

[0038] Measurement IC 110 is connected to each cell 62 of battery pack 60 via a signal line, and detects the cell voltage Vs of each cell 62.

[0039] As shown in FIG. 6, redundant circuit 120 is connected in parallel with relay 53. Redundant circuit 120 consists of diode 121 and semiconductor switch 123. Diode 121 connects cathode K to external terminal 51. One end of semiconductor switch 123 is connected to anode A of diode 121, and the other end is connected to the positive electrode of battery pack 60. The forward direction of diode 121 is the discharge direction of battery pack 60. By turning on semiconductor switch 123, even when relay 53 fails, battery pack 60 can supply power to vehicle 10 via redundant circuit 120.

[0040] Management device 150 is mounted on circuit board 100 (see FIG. 2) and, as shown in FIG. 5, includes CPU 151 and memory 153. Management device 150 is connected to points A and B in FIG. 5 via measurement lines L1 and L2, and can detect the terminal voltage V1 of battery 50 and the total voltage V2 of battery pack 60. Management device 150 is an example of a "fault diagnosis device".

[0041] The memory 153 stores an execution program of the fault diagnosis flow shown in FIG. 11 and data necessary for the execution of the program. The program may be stored in a recording medium such as a CD-ROM and used, transferred, lent, etc. The program may be distributed using a telecommunication line.

[0042] The voltage drop circuit 130 is connected to point A in FIG. 5 and drops the terminal voltage V1 of the battery 50 to a predetermined voltage such as "5V" and supplies it to the management device 150.

[0043] 2. Fault Diagnosis of Relay When the relay 53 has an "open fault (a fault where the contact 53a is stuck open)", the power supply to the vehicle 10 may be interrupted. Therefore, it is required to perform a fault diagnosis of the relay 53 to ensure the power supply to the vehicle 10.

[0044] When the contact 53a is "closed (normal)", the voltage V1 at point A and the voltage V2 at point B are substantially the same voltage, and if the battery pack 60 is charging or discharging, a current I equal to or greater than a predetermined value flows.

[0045] Therefore, it is conceivable to perform a fault diagnosis of the relay 53 based on the current I of the battery 50 and the voltages V1 and V2 at points A and B.

[0046] |V1 - V2| ≧ K (V) ····Equation (1) |I| ≦ K (I) ····Equation (2)

[0047] K (V) is a voltage threshold value determined based on voltage measurement errors, etc., and in this embodiment, it is 2 [V]. K (I) is a current threshold value determined based on current measurement errors, etc., and in this embodiment, it is 1 [A].

[0048] When both the voltage condition of Equation (1) and the current condition of Equation (2) are satisfied, the management device 150 may determine that the relay 53 has an "open fault".

[0049] When the management device 150 does not satisfy either the voltage condition of Equation (1) or the current condition of Equation (2), it is conceivable that the management device 150 determines that the relay 53 is "closed (normal)".

[0050] However, when diagnosing the failure of the relay 53 based on the two conditions of the voltage condition of Equation (1) and the current condition of Equation (2), depending on the state of vehicle systems such as the alternator 160 and the electrical load 170, the state of the contact 53a cannot be accurately detected, and there is a possibility of an incorrect diagnosis result.

[0051] Specifically, when the contact 53a is "open", the terminal voltage V1 of the battery 50 is equal to the voltage V3 of the power line 15 of the vehicle 10. When the voltage difference between V3 and V2 is small, V1 ≈ V2, and there is a possibility that the voltage condition of Equation (1) is not satisfied. Therefore, even if the contact 53a is actually "open", there is a possibility of erroneously determining that it is "closed (normal)".

[0052] When the management device 150 does not satisfy either the voltage condition of Equation (1) or the current condition of Equation (2), it temporarily closes the switch 53c to pass the exciting current Is from the battery pack 60 to the set coil 53b and holds the contact 53a in the "closed" state.

[0053] The voltage at point B (the voltage of the positive electrode of the battery pack 60) V2 changes from X [V] to Y [V] due to the discharge of the exciting current Is.

[0054] When the relay 53 is normal and the contact 53a is "closed", as shown in FIG. 8, the voltage at point A (the voltage of the positive external terminal 51) V1, like V2, changes from X [V] to Y [V] due to the discharge of the exciting current Is. On the other hand, when the contact 53a is "open" due to a failure of the relay 53, the voltage V1 at point A does not change due to the discharge of the exciting current Is and maintains X [V].

[0055] Thus, when the assembled battery 60 discharges the exciting current Is, the change in the voltage V1 at point A differs according to the state of the contact point 53a. Therefore, based on the voltage change ΔV1 at point A before and after the supply of the exciting current, it is possible to accurately determine whether the contact point 53a is "closed (normal)" or "open (faulty)".

[0056] In this embodiment, as shown in FIG. 9, the management device 150 calculates the voltage changes ΔV1 and ΔV2 of the voltage V1 at point A and the voltage V2 at point B before and after the supply of the exciting current. When ΔV1 = ΔV2, the management device 150 determines that the contact point 53a is "closed (normal)", and when ΔV1 ≠ ΔV2, the management device 150 determines that the contact point 53a is "open (faulty)".

[0057] ΔV1=(V1 1ST )-(V1 2ND ) ΔV2=(V2 1ST )-(V2 2ND ) V 1ST is the voltage before the supply of the exciting current, and V 2ND is the voltage after the supply of the exciting current.

[0058] With this configuration, in addition to improving the failure diagnosis accuracy of the relay 53, the following effects are obtained. In the failure diagnosis process, the exciting current Is is supplied to the set coil 53b, and the contact point 53a is held in the "closed" state. Therefore, even if the contact point 53a is switched from "closed" to "open" due to a malfunction of the relay 53, the contact point 53a can be returned to the "closed" state by executing the failure diagnosis.

[0059] For example, in the example of FIG. 10, in the previous failure diagnosis, after holding the contact point 53a in the "closed" state at time t1, at time t2, the relay 53 malfunctions and the contact point 53a is switched from "closed" to "open". However, thereafter, as a result of executing the failure diagnosis, the exciting current Is is supplied to the set coil 53b, and the contact point 53a is returned to the "closed" state at time t3.

[0060] The fault diagnosis flow of relay 53 will be described below with reference to FIG. 11. The fault diagnosis flow of relay 53 is composed of S10 to S150 and is executed, for example, at a predetermined execution cycle T during the startup of management device 150. Note that in the state before the flow execution, redundant circuit 120 is controlled to be off. Also, switches 53c and 53e of relay 53 are both off.

[0061] When the fault diagnosis flow starts, management device 150 measures current I of combined current 60, voltage V1 at point A, and voltage V2 at point B (S10). Current I can be measured by current detection unit 54, voltage V1 at point A can be measured by measurement line L1, and voltage V2 at point B can be measured by measurement line L2.

[0062] Thereafter, management device 150 determines the voltage condition of equation (1) based on the measured values of V1 and V2, and determines the current condition of equation (2) based on the measured value of current I of combined battery 60 (S20).

[0063] When management device 150 satisfies both the voltage condition of equation (1) and the current condition of equation (2) (S20: YES), it determines that relay 53 has an "open fault" (S30).

[0064] When management device 150 determines that relay 53 has an "open fault", it switches switch 123 of redundant circuit 120 from off to on. By switching switch 123 to on, discharge through redundant circuit 120 becomes possible, and power supply from combined battery 60 to vehicle 10 can be continued. Thus, the fault diagnosis flow ends.

[0065] Next, as a result of determining the voltage condition of equation (1) and the current condition of equation (2), when either condition is not satisfied (S20: NO), management device 150 measures voltage V1 at point A and voltage V2 at point B using measurement lines L1 and L2 (S100).

[0066] After measuring V1 and V2, the management device 150 switches the switch 53c from off to on to supply a pulsed excitation current Is from the battery pack 60 to the set coil 53b. As a result, the set coil 53b is excited, and if the relay 53 is normal, the contact 53a is held in the "closed" state.

[0067] Thereafter, the management device 150 re-measures V1 and V2 after the supply of the excitation current using the measurement lines L1 and L2 (S120).

[0068] Based on V1 and V2 before the supply of the excitation current measured in S100 and V1 and V2 after the supply of the excitation current measured in S120, the management device 150 calculates voltage changes ΔV1 and ΔV2 before and after the supply of the excitation current, respectively. The management device 150 compares ΔV1 and ΔV2 (S130).

[0069] When the voltage changes ΔV1 and ΔV2 at the two points A and B match (ΔV1 = ΔV2), the management device 150 determines that the relay 53 is "closed (normal)" (S140).

[0070] When the voltage changes ΔV1 and ΔV2 at the two points A and B do not match (ΔV1 ≠ ΔV2), the management device 150 determines that the relay 53 has an "open fault" (S150).

[0071] When the management device 150 determines that the relay 53 has an "open fault", it switches the switch 123 of the redundant circuit 120 from off to on. By switching the switch 123 to on, discharging through the redundant circuit 120 becomes possible, and the power supply from the battery pack 60 to the vehicle 10 can be continued. Thus, the fault diagnosis flow ends.

[0072] 3. Explanation of Effects In this configuration, regardless of the state of the vehicle system, it is possible to accurately determine whether the contact 53a is "open" or "closed". Therefore, the fault diagnosis accuracy of the relay 53 can be improved. By improving the fault diagnosis accuracy, it is possible to detect the open fault of the relay 53 at an early stage. When the open fault of the relay 53 is detected, by taking necessary measures such as operating the redundant circuit 120, it is possible to reduce the risk of the vehicle 10 suffering a power failure.

[0073] In this configuration, even if the contact 53a is unintentionally switched from "closed" to "open" due to a malfunction of the relay 53, the contact 53a can be returned to the "closed" state by performing fault diagnosis. Therefore, the risk of the vehicle 10 suffering a power failure can be reduced.

[0074] That is, in this configuration, since it is possible to "early detect an open fault" and "return to closed after a malfunction", it is possible to reduce the risk of a power failure and improve the reliability of the battery 50.

[0075] When determining whether the contact 53a is "open" or "closed" only based on the voltage change ΔV1 at point A before and after the supply of the exciting current, if the voltage V1 at point A changes due to factors other than the supply of the exciting current Is (for example, a voltage change in the vehicle power line 15), there is a possibility of misjudging the state of the contact 53a. In this configuration, by comparing the voltage change ΔV1 at point A and the voltage change ΔV2 at point B before and after the supply of the exciting current, even if the voltage V1 at point A changes due to factors other than the supply of the exciting current Is, it is possible to accurately determine whether the contact 53a is "open" or "closed". Therefore, the fault diagnosis accuracy of the relay 53 is high.

[0076] In this configuration, the management device 150 repeatedly executes the failure diagnosis process of the relay 53 (the failure diagnosis flow in FIG. 11) at a predetermined execution cycle T. By repeating the failure diagnosis process at the execution cycle T, the contact that has been switched to "open" due to the malfunction of the relay 53 can be restored to "closed" at the execution cycle T. Therefore, it is possible to prevent the contact 53 that has been switched due to a malfunction from remaining in the open state for a long time.

[0077] <Other Embodiments> The present invention is not limited to the embodiments described above and by the drawings. For example, the following embodiments are also included in the technical scope of the present invention.

[0078] (1) The secondary battery cell 62 is not limited to a lithium-ion secondary battery, and other non-aqueous electrolyte secondary batteries may also be used. The secondary battery cell 62 is not limited to the case where a plurality are connected in series and parallel, and may be connected in series or a single cell. Instead of the secondary battery cell 62, a capacitor can also be used. The secondary battery cell and the capacitor are examples of power storage cells.

[0079] (2) In the above embodiment, the battery 50 is mounted on the vehicle 10, but it may also be mounted on a moving body other than a vehicle, such as a ship or an aircraft. Since the battery 50 mounted on the moving body is exposed to vibrations accompanying the movement of the moving body, it is more likely to malfunction (operation of the relay 53 not intended) compared to a stationary power storage device. Also, not limited to moving bodies, the battery 50 can be used for other applications as long as the application does not allow power failure.

[0080] (3) In the above embodiment, the redundant circuit 120 is provided in parallel with the relay 53, but the redundant circuit 120 may be omitted.

[0081] (4) In the above embodiment, the failure diagnosis flow of the relay 53 is composed of S10 to S150. The processes of S10 and S20 may be omitted, and only S100 to S150 may be used to diagnose the open failure of the relay 53.

[0082] (5) In the above embodiment, the failure of relay 53 was determined based on the voltage changes ΔV1 and ΔV2 before and after the supply of the exciting current. Specifically, when the voltage changes ΔV1 and ΔV2 between point A and point B are the same (ΔV1 = ΔV2), relay 53 was determined to be "closed (normal)", and when they are different (ΔV1 ≠ ΔV2), relay 53 was determined to have an "open failure". Any determination method may be used as long as the failure of relay 53 is determined based on the voltage change ΔV1 at point A before and after the supply of the exciting current. For example, by supplying the exciting current Is from the battery pack 60 to the set coil 53b, when the voltage V1 at point A changes compared to before the supply of the exciting current, the contact 53a may be determined to be closed (normal), and when the voltage V1 at point A does not change, the contact 53a may be determined to be open (failed).

Explanation of Reference Numerals

[0083] 10 Vehicle 50 Battery (Power Storage Device) 53 Relay 53a Contact 53b Set Coil (First Coil) 53c Switch 53d Reset Coil (Second Coil) 53e Switch 54 Current Detection Unit 60 Battery Pack 110 Discharge Circuit 120 Redundant Circuit 150 Management Device (Fault Diagnosis Device)

Claims

1. A power storage device, comprising: an external terminal; a power storage cell; a relay having one end electrically connected to the external terminal and the other end electrically connected to the power storage cell; a fault diagnosis device, wherein the relay is a contact; a first coil that holds the contact in a closed state when an exciting current is supplied from the power storage cell; a second coil that holds the contact in an open state when an exciting current is supplied from the power storage cell, and is a normally-closed type latching relay; wherein, in the fault diagnosis process of the relay, the fault diagnosis device holds the contact in a closed state by supplying an exciting current from the power storage cell to the first coil, and diagnoses an open fault of the relay based on a comparison result between a voltage change ΔV1 of the external terminal and a voltage change ΔV2 of the power storage cell before and after the supply of the exciting current. When ΔV1 = ΔV2, it is determined to be normal, and when ΔV1 ≠ ΔV2, it is determined to be faulty. The power storage device.

2. The power storage device according to claim 1, wherein the fault diagnosis device repeatedly executes the fault diagnosis process of the relay at a predetermined execution cycle. The power storage device.

3. The power storage device for a moving body according to claim 1 or claim 2.

4. A method for diagnosing a fault of a relay, wherein the relay is a normally-closed type latching relay having one end electrically connected to an external terminal and the other end electrically connected to a power storage cell, supplying an exciting current from the power storage cell to a first coil to hold a contact of the relay in a closed state; diagnosing an open fault of the relay based on a comparison result between a voltage change ΔV1 of the external terminal and a voltage change ΔV2 of the power storage cell before and after the supply of the exciting current. When ΔV1 = ΔV2, it is determined to be normal, and when ΔV1 ≠ ΔV2, it is determined to be faulty. The method for diagnosing a fault of a relay.

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